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Appendix VI.                          1145

^. /Of3.

'balls to the normal. A spring attached to H resists the tendency
of the governor shaft to over-run, being tightened to any desired
extent. This governor has proved very successful on some
hundreds of ships, both naval and mercantile.

The Shaft Governor, Fig. 652, p. 657, as already ex-
plained, alters the expansion by a decrease of eccentric travel, and
the method has one distinct advantage: the lead can be kept
constant for all positions of cut-off. Referring to Fig. 1014, oc
is the engine crank, and o A the eccentric crank at fullest opening.
Explaining by a Zeuner diagram, the throw is decreased from o A
to o B, and the cut-off position of the engine crank changes from
o E to o F, when p is the dead-point of commencement. The two
Zeuner circles, o A and o B, both pass through the same point M